The Science of Imagination
by Cherish the look of surprise
Summary: The consulting detective has got a new case. Two tourists have been murdered and the only clue he has to go on is their six year old son who witnessed it all. Unfortunately it seems that Calvin, and his stuffed tiger Hobbes, aren't that keen to co-operate. Alternating fluff and angst depending on my mood.
1. Chapter 1 - An American in London

**Chapter 1 – An American in London**

"Sir, the case from this morning. It seems it's more complicated than we originally thought." Lestrade sighed as Donovan's depressing words washed over him. What fresh hell is it now?

"What could've possibly happened between the two minutes it took me to get a cup of coffee? Are the Americans kicking up a fuss again? Because you can tell Mr Up his own arse Mitchell that I have done everything I possibly could to get those files to him. Just because two tourists get murdered here does not mean I owe him a damn thing! So he can stuff his opinions where the sun don't shine!" During his furious tirade, Greg had gotten up and started pacing around the broom cupboard he called an office, readying himself to tell Mr Mitchell this in person.

"No, it's something else. That couple, they… they had a child. And he's still alive. It seems he was hiding in the wardrobe while the murderer shot his parents. He heard everything. This boy could be the key to this investigation." Sally shifted uncomfortably, not used to such a display of emotion from her usually reserved boss. She watched as Greg sank back down into his chair, the anger drained from his face.

"No way. No bloody way. A child? You're telling me that in the hours that our forensic team spent at that bloody hotel no one noticed that their child was STILL BLOODY THERE!" Sally bowed her head, trying to make herself a smaller target. She started mumbling excuses, anything to calm Lestrade down.

"Well you see sir he didn't make any noise as he was still in shock and he barred the door to the wardrobe with some sort of stuffed tiger and it was only when he started screaming that the forensic team realised he was there and even then they had to sedate him because he was absolutely out of control, he kept on screaming and fighting and nobody knew what to do so…" She trailed off, watching Greg warily. But Lestrade had managed to calm himself down, breathing deeply and counting back from ten. It was that or a murderous rampage through the office. Unfortuantely Lestrade couldn't be arsed with all the paperwork involved so calming down it was.

"Does this kid have a name?"

"Yes sir." Sally, glanced at the stack of files in her arms.

"His name is Calvin."


	2. Chapter 2 - The Return of Spaceman Spiff

"A child?" When Lestrade had asked him to come down to the station, John Watson had not been expecting this.

"An actual child?" Hearing the incredulity colour the doctor's voice, Lestrade merely grimaced and nodded. Just one more problem to dump on top of this already crap day, though maybe not how the kid saw it. To him this day would be the day his parents died. And Lestrade couldn't do a damn thing about it, apart from one.

"It's terrible. But we need Sherlock. The boys are baying for blood, and they don't care who brings it. Even Anderson wants Sherlock on this. Why isn't he here?" He looked around, half expecting the consulting detective to pop out from somewhere and start deducing what he had for breakfast from his left knuckle.

"He's in Brighton for a case, but he'll be back later today. Is there anything I can do in the mean time? I know I'm not a consulting detective, but I might be of some use." John chuckled weakly before sighing and adding more sugar to his tea. Of all the times for Sherlock to take one of Mycroft's cases, it had to be now. Sod's law he supposed.

"Well there is something you can do…" Lestrade hesitated, was this going too far?

"Anything."

"Could you take the kid in for a little while? No care home will take him and all his relatives are gone except for an Uncle Max somewhere. But apparently he had some falling out with the family and refuses to acknowledge the child. And besides, it might give Sherlock more time with the kid and to crack this case." He eyed John nervously, this was his last resort but he had to give it a go. No matter how many nightmares the words "Sherlock" and "child" in the same sentence conjured up. If it helped solve this case he would do anything. Even risk traumatising the kid further.

"Of course! We'd be happy to. Well… I am." They both winced as they imagined what hell would break loose. Still, that was a problem for tomorrow.

"So, can I see him? Calvin, I mean." John should probably work out what he was getting himself into before promising anything. And yet he knew it was too late. No matter what Sherlock said, they were going to help Calvin.

"Sure, he's in my office. He had to be sedated when they got him out of… _there_. Hopefully woken up now." Both men got up, leaving the lukewarm tea for more important matters. John prayed that he could help the poor thing. He must be so upset and scared. What a horrible crime. Disgusting what people can do. Lestrade however was considering all the possible locations this killer could be. He may not have a homeless network, but he did have a few contacts. This guy was going to get what was coming to him. For what he did, not just to the victims but to their son.

"Let's see if we can't wake him up. Easy does it." Speaking in hushed tones to the man beside him, Lestrade eased open the door, expecting to see a lonely child curled up on a chair.

What he was not expecting was that same child to be pointing a gun at him.

"BANG! BANG! Spaceman Spiff shoots the strange aliens with their primitive technology! Evading capture in enemy territory he defeats the creatures with ease, destroying hundreds of them with a single bound! You'll never take me alive! NEVER! Take cover Hobbes!" The blonde child and his stuffed tiger hid behind a filing cabinet, occasionally checking on the two shell-shocked men before ducking back in.

There was a lengthy silence, the only sound of Calvin's heavy breathing.

"Where did he get a gun?"

"Top drawer. Should've locked it."

"Oh."

"This is Calvin."

"I gathered."

"We may have to get a psychiatrist in."

"NO! NO MORE SHRINKS!" Calvin finally left his spot behind the cabinet, instead racing out the door, his tiger trailing behind him as various members of the police department watched in confusion. And still the men could do no more than watch him.

"Should we go after him?"

"Yeah, probably."

And off they ran too.

But it turns out the stamina of a six year-old child is far higher than that of two middle aged men. Until said six year-old takes a break to get a snack from the staff room.

"Hey!" He panted "Stop!" Lestrade called out to the kid as he finally spotted him in front of the vending machine. Calvin got ready to run again before John appeared on his other side, just as out of breath.

"Don't worry! We're not going to hurt you! We just want to talk." Lestrade and John crept closer, getting ready to tackle the blonde missile.

"The aliens are closing in! WHAT WILL SPACEMAN SPIFF DO?! DUN DUN DUN!" And with that, Calvin dived through Lestrade's legs and sprinted off, laughing all the way.

"Is it wise to put him and Sherlock in the same room?"

"Is it wise to put anyone and Sherlock in the same room?"

"Fair enough."

And they resumed the chase.

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**A longer chapter, because you've been so good :)**

**Hey! Sorry I haven't posted in a while. Too busy procrastinating...**

**But I'm back for good now.**

**Enjoy!**

**Bx**


	3. Chapter 3 - Tales and Tea

"So this is our flat. You'll be living here for a little while, ok?" John led Calvin up the steps of 221b, one hand on his rucksack, the other grasping his shoulder tightly, just in case he tried to make a run for it. Again.

Calvin merely glared. Glared at the door, glared at the street, glared at John. It was all he had done after Lestrade and John cornered him between the fire exit and stationary cupboard. Well, that and bite. But he deserved time to adjust; his parents had been murdered in front of him for god's sake! It did hurt though.

Rubbing his arm absent-mindedly, John unlocked the door and ushered Calvin inside and towards the smiling old woman who inhabited the flat downstairs.

"This is Mrs Hudson, she's our housekeeper. Makes the best tea in all of England she does."

"Oh nonsense! And I'm still not your housekeeper." Shaking her head in exasperation, she smiled down at the scowling child. "So, you're Calvin then? Lovely name that, nice name for a nice boy."

But to John's horror (and slight amusement) the devious little child began another one of his elaborate fantasies.

"The dame was still yappin', but my mind had gone to the whiskey on my desk and the bullets in my .44 magnum. Her goon had taken both away, but Tracer Bullet always has a back-up. No matter how tough the case is. They wouldn't tell me a single thing, just that we had to wait till the 'big boss' got here. Well I don't know about you, but I wasn't too keen on stayin' to meet him."

As fast as he could, John shoved the kid up the stairs, hurrying up behind him to the sound of Mrs Hudson yelling:

"Did that little scamp just call me a 'dame'?!"

"Time to go kid!"

"Ow! No need to shove! I'm going, I'm going!"

The door slammed behind them with a thud.

"So that was Mrs Hudson, and here's the flat. You'll be sleeping in my ro-" John was interrupted by Calvin once again running off. Not towards the door as he had thought, but towards the mantel piece. He winced at the excited exclamation that followed.

"A skull! Cool! Look Hobbes, a real skull!" It was sweet how he kept on talking to his tiger, like it was real. Probably from the trauma of the accident or something. John hadn't realised he had spoken those words aloud until Calvin replied:

"He's not sweet, he's a ferocious man-eating tiger who could crush you with a single swipe of his paw." Waving the tiger's paw around for effect. The lecture probably would've gone on for longer had he not been distracted by a rather precarious and dangerous looking chemistry experiment on the kitchen table that Sherlock had left behind with strict instructions not to tamper with.

Desperately trying to divert Calvin from his path of destruction, John guided him away from the poisonous chemicals and back to the bedroom he would be sleeping in. Unfortunately Calvin ducked out of his grip and ran back to the table, awe struck by the bubbling liquids. Was he going to have to invest in a leash or something? But just as he was about to drag him back, the mischievous little kid said the most astonishing thing:

"Hey! Isn't that the experiment measuring the reaction of explosive polymerization in a compressed state?"

There was a lengthy pause as Calvin continued gazing at the experiment and John desperately tried to work out how on earth he could've known that. The only reason John knew it was because of Sherlock explaining in great detail why he couldn't throw it away. But somehow Calvin could immediately deduce what it was with barely a glance.

Deciding that trying to get him to sit quietly somewhere would be an impossible task, John thought that distracting him with questions would be better.

"So, you like science? That's great, I liked science when I was younger and now I'm a doctor. Was your dad a scientist? Is that how you knew all of that?" Seeing as his parent's murder didn't seem like the best subject to discuss, John felt it best to stick with this latest mystery.

"Nah, only the fun parts. Like explosions. Although once I stuck some of Susie Derkin's hair in a beaker of sulphuric acid. That was cool!" Completely missing John's look of worry and unease, he ploughed on. "And no, my dad isn't a scientist. He's got a super boring job. Nothing cool like an astronaut or a detective."

"So you think detectives are cool? Well, as it so happens, my friend Sherlock is a detective. You'll be able to meet him soon."

"A detective! Wow! Does he go out and shoot bad guys before getting cornered in dark alley way by a big mafia boss' goons?" Calvin jumped up on the sofa, miming shooting an imaginary gun at John, seeming most put out when he didn't collapse, wounded.

"Not really. He more solves cases. Although there have been a few times where we almost got killed."

Calvin's eyes lit up at the news, practically vibrating with excitement. John knew he shouldn't be encouraging the kid's belief that violence was 'cool' but so far this was the longest he had gone without making a break for it. So to give his aching legs a rest, he shared his and Sherlock's stories. Cases going wrong, capturing the bad guys, aggravating Lestrade and Mycroft, always making sure to gloss over the gory parts. This bonding carried on for a long time, longer than either party realised, until John was half way through 'The case of the green man.'

"So there we were, me and Sherlock, crouching behind this van as the smugglers were loading the goods onto the ship, when suddenly Sherlock pushes me into the view of over thirty criminals and goes-"

"You distract them while I call Lestrade. Good evening John, why have we acquired a small child? Did you doubt my return? Or has your relationship with Leila progressed faster than I had originally anticipated?"

Sherlock was home.

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**Yes I'm late, yes I'm a horrible person, but look! Shiny new chapter! *ducks***

**Happy one year anniversary Secret Agent Codename Bob, it's been a hell of a good one.**

**Congrats to Myrna Maeve, who hit the nail on the head with her review. Calvin's lack of traumatisation will be explained, I promise.**

**Thank you for sticking with it, and hopefully I stop messing about and upload a new one :)**

**Bxx**


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